A good Samaritan trying to intervene in a fight was beaten with a cane in the South of Market neighborhood of San Francisco on the Fourth of July, officials said.The passerby intervened and tried to break up the fight, but the man involved in the altercation beat him with a cane, then fled west on Mission Street, police said.The assaulted do-gooder was taken to a hospital with non-life-threatening injuries, according to police.